It is known that salts which have been sterilized by radioactive radiation become discolored. A probable explanation of this discoloration is that it is due to an electron displacement, that is to say to one or more electrons being caused to change their electron orbit, and thereby entering into an excited state.
Unpublished experiments which have been directed to restoring the original color of these irradiated salts have been carried out with the help of daylight, UV-light and microwaves. However, these experiments have not evidenced any success.
Alternatively, it is possible to refrain entirely from the use of such irradiation, and to use instead a bacteria filter for the filtering out of undesirable substances after the salt has been dissolved in water or other suitable liquids In this case, however, difficulties can arise in maintaining the bacteria filter sterile. These difficulties may be overcome in the manner which is described, for example, in U.S. Pat. No. 4,783,273.
A further alternative method to such irradiation consists in using a powder which is as pure as possible, and dissolving that powder directly in connection with its utilization, see, for example, U.S. Pat. No. 4,784,495.It is not possible in such case, however, to guarantee absolute sterility.